biequivalent

Both left equivalent and right equivalent; Having the property that there exists a pair of mappings M₁ (A->B) and M₂ (B->A) such that M₁M₂(A) is equivalent to applying the unity operator to A and M₂ M₁(B) is equivalent to applying the unity

We define strict and weak duality involutions on 2-categories, and prove a coherence theorem that every bicategory with a weak duality involution is biequivalent to a 2-category with a strict duality involution.

Capable of replacing a bond formed by H₂ to any molecule.

This is chloride of ammomium, in which 2 atoms of hydrogen are displaced by the biequivalent atom of mercury.